The next spot on our chromatograph is Red 40, or Allura Red AC. Here is its structure:

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Here’s one of our paper chromatography spots - the yellow dye is the beloved Yellow #5, or tartrazine:

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99 years ago, a Japanese researcher was looking into some puzzling stuff. A broth of kelp, when boiled down, yielded some brown crystals that tasted like, well, essence of savoriness. “Savory” is one of those flavors that is hard to pinpoint - for salty, sweet, sour, bitter, we have archetypes - sugar, sodium chloride, lemon juice, and alkaloids, which you don’t taste on their own very often. As Barry Sharpless noted, he won’t taste a compound with a nitrogen atom in it - these are the bulk of our alkaloids, many of which are psychotropic (not nearly all, though). The best everyday example of a bitter compound I can think of is tonic water, which is bitter due to the alkaloid quinine.

Anyway, savoriness, or “umami,” as he put it, is hard to pinpoint. Those crystals he found came close, which were those of the much-maligned monosodium glutamate, or MSG:

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This is the yellow pigment in turmeric, the spice responsible for curries being nuclear holocaust yellow.

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In what seems to be de rigeur for artificial sweeteners, sucralose (Splenda) was discovered by accident, when some careless soul tasted it. From Wikipedia:

Sucralose was discovered in 1976 by scientists from Tate & Lyle, working with researchers at Queen Elizabeth College (now part of King’s College London). It was discovered by Leslie Hough and a young Indian chemist Shashikant Phadnis. The duo were trying to make an insecticide. On a late-summer day, Phadnis was told to test the powder. Phadnis thought that Leslie asked him to taste it; so he did. He found the compound to be ridiculously sweet (the final formula was 600 times sweeter than sugar). They worked with Tate & Lyle for a year before settling down on the final formula. They did not find any use of the compound as an insecticide.

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Friday, we talked about about carvone. I mentioned that it comes from the same biosynthetic pathway as cholesterol. The precursor to this, as well as a number of other natural products, is isopentenyl pyrophosphate, which we’ll refer to as IPP:

A few things this ends up in are compounds like carvone, limonene, and menthol, shown below:

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The other day we talked chirality. Here’s the example they give in every organic chemistry class when they’re teaching chirality. Carvone!

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Have you ever wondered whether you would swim faster in syrup or water? I hadn’t, either, until I found out someone had actually brought a swimming pool up to to Mrs. Butterworth’s-level viscosity and had people swim in it. Then I became intensely curious.

Proell admits he was slightly taken aback when he first heard Cussler’s proposal to dump 700 pounds of guar gum, a thickening agent, into one of the University’s pools. Fortunately, though, he recognized the proposal’s educational merits.

“Cussler is persuasive, but we didn’t need much persuading. We all agreed that we had an opportunity here to be part of the University’s educational mission. [The experiment] involved movement through water. [I]n aquatics, that’s our business. It intrigued us.”

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Mercury is a weird one. It’s quite toxic, and you’ll do well not to handle it casually, but as the metal it’s actually not that bad. If a thermometer breaks, you can probably clean up the area as best you can, then sprinkle zinc dust or sulfur (disputed, see here) on it to keep it from evaporating. If you spill it in, say, an oven, like in the lab, or spill a great deal, it can be a bigger problem - some labs have mercury bubblers with literally pounds of the stuff in them - for most applications, you can use mineral oil, but especially in academic labs, you see a lot of mercury still floating around.

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Capsaicin is a molecule expressed by chiles (genus capsicum - this includes all pepper fruits, from jalapeno to habanero). It induces the familiar burning sensation. It, or its cousin, dihydrocapsaicin, is responsible for the hotness in essentially all hot sauces. Here is its structure:

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